You charge $50 for a bunch of color codes and text? That's the biggest rip off I have ever seen. I'd be willing to do it for free, heck, anyone can do it.
Yes, anyone can do it themselves if they want to take time and learn the code. $10 is a reasonable price for a custom signature design. Would you be willing to do it
for free for 100 users a month?
For $10 I can do a custom signature design like this one:
http://d.pr/i/LNEQBelieve me, it takes about an hour to make it, so I think the price is fair